With training camp opening Friday, one of the intriguing subplots will be watching Vontae Davis and Sean Smith grow after rookie seasons in which Peyton Manning, Reggie Wayne and others praised the young cornerbacks.

This summer, Dolphins people have been especially effusive about Davis, ``who has gone from someone with potential to fulfilling that potential,'' receiver Greg Camarillo said.

But this much is clear: Davis and Smith (and the team's safeties) must do a better job preventing the big play for this defense to be as aggressive as coordinator Mike Nolan wants. Washington's Vonnie Holliday, who played under Nolan in Denver, said Nolan has to trust his defensive backs will not be burned deep for him to send as many pass rushers as he prefers.

Consider: ProFootballFocus ranked 107 cornerbacks' 2009 performance. Smith was worst in the league in average yards per completion in the player's coverage area (19.8 average on 38 receptions). Davis was fourth-worst (17.4 on 48 receptions). Will Allen, who has vowed to get his starting job back, was 22nd-worst (13.8) before his knee injury in the sixth game.

Here's the good news: Allen and Smith were well above average in percentage of passes completed into their coverage -- Allen's 37.9 percent was second-best behind only Darrelle Revis. Smith was 36th-best at 56.7 percent and Davis 65th at 63.2 percent.

And for their overall play in 2009, the website ranked Allen 26th, Davis 27th and Smith 32nd among 107 corners.

Camarillo sees it: ``Vontae is probably the best athlete on the team, and he relied on athleticism at first. Now, he has greatly improved his technique and covering routes.''

Davis studied tapes of Al Harris and Charles Woodson, two of his favorite corners, and ``what I've learned is it's about being a professional. I know if I have a day off, I'm going to rest my body. Last year, I wanted to hang out with family, be out playing.''

Smith, meanwhile, said he will stop being too cautious. ``So many times last year, I was afraid to make a mistake because we were in so many close games,'' he said. ``In certain situations, I was too hesitant, gave up too much cushion, not aggressive. You can't play safe all the time. That comes with studying more, knowing when to take chances.''

Smith had no interceptions -- Davis had four -- and guarantees he will have at least one in 2010. ``Last year, everyone was saying we're Pat Surtain and Sam Madison all over again,'' Smith said. ``With that kind of pressure, you're kind of overwhelmed.''

And now? ``I'm a lot more confident, starting to feel like a real vet,'' he said.

Even if Allen beats out Smith -- which is possible if Allen's knee is 100 percent -- all three will play a lot. ``I don't see why I shouldn't start,'' Smith said.

Well I hope Davis didn't change that much...he was excellent a year ago.

He definitely was. Big time playmaker. 5 INT's as a rookie is unbelievable when you think about it. He did get beat some, but a lot of that was because of 1) no safety help, 2) no pass rush, 3) Paul Pasqouloni being an idiot and matching him up 1v1 against Moss, TO, etc. consistently with no safety help and no blitz.

Well I hope Davis didn't change that much...he was excellent a year ago.

He definitely was. Big time playmaker. 5 INT's as a rookie is unbelievable when you think about it. He did get beat some, but a lot of that was because of 1) no safety help, 2) no pass rush, 3) Paul Pasqouloni being an idiot and matching him up 1v1 against Moss, TO, etc. consistently with no safety help and no blitz.